This invention relates to a circuit for generating a frequency-modulated signal and in particular for generating such a signal indicative of data to be recorded on magnetic tape.
It is usual practice in frequency-modulated data recording to render the centre frequency of the frequency-modulated carrier signal proportional to the tape speed selected for recording.
Generally, the selectable tape speeds bear a binary relationship to one another, so that the frequency of the carrier signal corresponding to the selected tape speed can be provided by binary division of the frequency of the generated signal.
However, it has been found that simple binary division of the frequency may not provide a sufficiently accurate correlation between the frequency and tape speed, particularly in certain applications where an intermediate or a continuously variable tape speed is utilised.